Bottom Line:
The reporting of these studies was often inadequate, in terms of both statistical analysis and presentation, and there was considerable heterogeneity for many important clinical/statistical factors.General availability of full individual patient data is a necessary step forward and would overcome the majority of problems encountered, including poorly reported summary statistics and variability in cutoff level, outcome assessed and adjustment factors used.Such changes in practice would help important evidence-based reviews to be conducted in order to establish the most appropriate prognostic markers for clinical use, which should ultimately improve patient care.

Affiliation: Department of Epidemiology and Public Health, University of Leicester, Leicester, UK. rdr3@leicester.ac.uk

ABSTRACTPrognostic markers help to stratify patients for treatment by identifying patients with different risks of outcome (e.g. recurrence of disease), and are important tools in the management of cancer and many other diseases. Systematic review and meta-analytical approaches to identifying the most valuable prognostic markers are needed because (sometimes conflicting) evidence relating to markers is often published across a number of studies. To investigate the practicality of this approach, an empirical investigation of a systematic review of tumour markers for neuroblastoma was performed; 260 studies of prognostic markers were identified, which considered 130 different markers. The reporting of these studies was often inadequate, in terms of both statistical analysis and presentation, and there was considerable heterogeneity for many important clinical/statistical factors. These problems restricted both the extraction of data and the meta-analysis of results from the primary studies, limiting feasibility of the evidence-based approach.Guidelines for reporting the results of primary prognostic marker studies in cancer, and other diseases, are given in order to facilitate both the interpretation of individual studies and the undertaking of systematic reviews, meta-analysis and, ultimately, evidence-based practice. General availability of full individual patient data is a necessary step forward and would overcome the majority of problems encountered, including poorly reported summary statistics and variability in cutoff level, outcome assessed and adjustment factors used. It would also limit the problem of reporting bias, although publication bias will remain a concern until studies are prospectively registered. Such changes in practice would help important evidence-based reviews to be conducted in order to establish the most appropriate prognostic markers for clinical use, which should ultimately improve patient care.

fig2: Description of the key reporting problems that prevented estimation of the loge(hazard ratio) and its variance in 371 (64.5%) of the reports

Mentions:
Primary studies of prognostic tumour markers are clearly essential and we observed many important results across the literature that have implications for clinical practice. However, the general standard of reporting primary studies was inadequate, and it was disappointing that we only managed to obtain 35.5% of the estimates required despite the intensive, time-consuming extraction procedure (Figure 1). This hindered the use and interpretation of meta-analysis because we could not incorporate the majority of results reported in the literature and consequently introduced a strong potential for bias. Among the 371 reports that did not enable estimates to be made, there were five common reporting problems, most of which can be simply addressed (Figure 2Figure 2

fig2: Description of the key reporting problems that prevented estimation of the loge(hazard ratio) and its variance in 371 (64.5%) of the reports

Mentions:
Primary studies of prognostic tumour markers are clearly essential and we observed many important results across the literature that have implications for clinical practice. However, the general standard of reporting primary studies was inadequate, and it was disappointing that we only managed to obtain 35.5% of the estimates required despite the intensive, time-consuming extraction procedure (Figure 1). This hindered the use and interpretation of meta-analysis because we could not incorporate the majority of results reported in the literature and consequently introduced a strong potential for bias. Among the 371 reports that did not enable estimates to be made, there were five common reporting problems, most of which can be simply addressed (Figure 2Figure 2

Bottom Line:
The reporting of these studies was often inadequate, in terms of both statistical analysis and presentation, and there was considerable heterogeneity for many important clinical/statistical factors.General availability of full individual patient data is a necessary step forward and would overcome the majority of problems encountered, including poorly reported summary statistics and variability in cutoff level, outcome assessed and adjustment factors used.Such changes in practice would help important evidence-based reviews to be conducted in order to establish the most appropriate prognostic markers for clinical use, which should ultimately improve patient care.

Affiliation:
Department of Epidemiology and Public Health, University of Leicester, Leicester, UK. rdr3@leicester.ac.uk

ABSTRACTPrognostic markers help to stratify patients for treatment by identifying patients with different risks of outcome (e.g. recurrence of disease), and are important tools in the management of cancer and many other diseases. Systematic review and meta-analytical approaches to identifying the most valuable prognostic markers are needed because (sometimes conflicting) evidence relating to markers is often published across a number of studies. To investigate the practicality of this approach, an empirical investigation of a systematic review of tumour markers for neuroblastoma was performed; 260 studies of prognostic markers were identified, which considered 130 different markers. The reporting of these studies was often inadequate, in terms of both statistical analysis and presentation, and there was considerable heterogeneity for many important clinical/statistical factors. These problems restricted both the extraction of data and the meta-analysis of results from the primary studies, limiting feasibility of the evidence-based approach.Guidelines for reporting the results of primary prognostic marker studies in cancer, and other diseases, are given in order to facilitate both the interpretation of individual studies and the undertaking of systematic reviews, meta-analysis and, ultimately, evidence-based practice. General availability of full individual patient data is a necessary step forward and would overcome the majority of problems encountered, including poorly reported summary statistics and variability in cutoff level, outcome assessed and adjustment factors used. It would also limit the problem of reporting bias, although publication bias will remain a concern until studies are prospectively registered. Such changes in practice would help important evidence-based reviews to be conducted in order to establish the most appropriate prognostic markers for clinical use, which should ultimately improve patient care.